... rate:250 wireless voice doorbell with clear voice for hot sell 1V21,2.4G ISM Public Frequency Band:2402MHz-2479MHz2,Transfer rate:250K ... is busy, then drops twice, busy prompt ,refund standby. F:In the process of waiting for the off-hook, press CALL ... key again 1,If Indoor monitor in the ring , then it doesn't ring again, Outdoor monitor ...